An outbreak of acquired immunodeficiency syndrome (AIDS) is occurring in Haitian residents in Miami, Florida. These AIDS patients have the characteristic defects in cell mediated immunity associated with an increased susceptibility to opportunistic infections such as Pneumocystis carinii (PC), Toxoplasm gondii and disseminated Herpesvirus. Laboratory data reveals that Haitian patients with AIDS have T-lymphocyte subset abnormalities, dysgammaglobulinemias, and circulating immune complexes similar to those noted in male homosexuals with AIDS. As has been noted in male homosexuals with AIDS, Haitians with AIDS have a markedly increased rate of Kaposi's sarcoma (KS). We have also described an infant form of AIDS in 13 Haitian children born to mothers with marked immunologic abnormalities. Recently two of these infants have been found to have KS and represent the first reports of childhood KS in this country. Haitians also have a relatively high incidence of human T-cell leukemia/lymphoma virus (HTLV) infections (28%) as measured by serum antibody to HTLV-specific cell surface antigens. The presence of HTLV in the Haitian population and the association of HTLV with AIDS in male homosexuals suggest that HTLV may play some role in the pathogenesis of AIDS among Haitians. In order to study HTLV infection in this population it is first necessary to define detection methods and to investigate the pathogenesis of HTLV infection in both AIDS patients and contacts. The present proposal is for the study of HTLV-virus-host interactions. We will quantitate HTLV polypeptides and nucleic acid sequences in peripheral blood leukocytes from antibody-positive and negative Haitians. Tissues from patients with and without AIDS will also be examined for HTLV both in biopsy and autopsy materials. Isolation of HTLV as well as immunologic studies of already existing HTLV antibody-positive Haitian sera will be undertaken to provide information on the correlation between patient's serologic reactivity and HTLV genetic divergence. Immune responses to HTLV will be measured in terms of immunoglobulin classes, temporal expression and the virion polypeptides and/or precursors involved in stimulating natural immunity. These immune responses will be correlated with clinical conditions to determine potential prognostic factors. as soon as adequately sensitive and specific assays are characterized, sera collected from Haitians in Miami as part of a prospective multicenter CDC collaborative case control study and from hospital and laboratory staff will be examined for evidence of HTLV infection.